The buzz within: the role of the gut microbiome in honeybee social behavior.

Gut symbionts influence the physiology and behavior of their host, but the extent to which these effects scale to social behaviors is an emerging area of research. The use of the western honeybee (Apis mellifera) as a model enables researchers to investigate the gut microbiome and behavior at several levels of social organization. Insight into gut microbial effects at the societal level is critical for our understanding of how involved microbial symbionts are in host biology. In this Commentary, we discuss recent findings in honeybee gut microbiome research and synthesize these with knowledge of the physiology and behavior of other model organisms to hypothesize how host-microbe interactions at the individual level could shape societal dynamics and evolution.

Electricity generation by thermophilic microorganisms from marine sediment.

The search for microorganisms that are capable of catalyzing the reduction of an electrode within a fuel cell has primarily been focused on bacteria that operate mesobiotically. Bacteria that function optimally under extreme conditions are beginning to be examined because they may serve as more effective catalysts (higher activity, greater stability, longer life, capable of utilizing a broader range of fuels) in microbial fuel cells. An examination of marine sediment from temperate waters (Charleston, SC) proved to be a good source of thermophilic electrode-reducing bacteria. Electric current normalized to the surface area of graphite electrodes was approximately ten times greater when sediment fuel cells were incubated at 60 degrees C (209 to 254 mA/m(2)) vs 22 degrees C (10 to 22 mA/m(2)). Electricity-generating communities were selected in sediment fuel cells and then maintained without sediment or synthetic electron-carrying mediators in single-chambered fuel cells. Current was generated when cellulose or acetate was added as a substrate to the cells. The 16S ribosomal ribonucleic acid genes from the heavy biofilms that formed on the graphite anodes of acetate-fed fuel cells were cloned and sequenced. The preponderance of the clones (54 of 80) was most related to a Gram-positive thermophile, Thermincola carboxydophila (99% similarity). The remainder of clones from the community was most related to T. carboxydophila, or uncultured Firmicutes and Deferribacteres. Overall, the data indicate that temperate aquatic sediments are a good source of thermophilic electrode-reducing bacteria.

Stress and vowel duration effects on syllable recognition.

Systems designed to recognize continuous speech must be able to adapt to many types of acoustic variation, including variations in stress. A speaker-dependent recognition study was conducted on a group of stressed and destressed syllables. These syllables, some containing the short vowel /I/ and others the long vowel /ae/, were excised from continuous speech and transformed into arrays of cepstral coefficients at two levels of precision. From these data, four types of template dictionaries varying in size and stress composition were formed by a time-warping procedure. Recognition performance data were gathered from listeners and from a computer recognition algorithm that also employed warping. It was found that for a significant portion of the data base, stressed and destressed versions of the same syllable are sufficiently different from one another as to justify the use of separate dictionary templates. Second, destressed syllables exhibit roughly the same acoustic variance as their stressed counterparts. Third, long vowels tend to be involved in proportionally fewer cross-vowel errors but tend to diminish the warping algorithm's ability to discriminate consonantal information. Finally, the pattern of consonant errors that listeners make as a function of vowel length shows significant differences from that produced by the computer.

Vowel height and the perception of consonant nasality.

By means of an articulatory synthesizer, the perception of the oral-nasal distinction in consonants was explored experimentally. This distinction was chosen because it is achieved by a very simple articulatory maneuver and because it is phonologically relevant in virtually every language. Lowering the velum in equal increments provided continua of CV syllables varying in size of velopharyngeal port which were divided perceptually into /d/ and /n/ categories by American English listeners. To test the hypothesis that the coarticulation of these nasal consonants with lower (more open) vowels requires a larger area of velopharyngeal coupling to give a nasal consonant precept, three oral-nasal continua incorporating the vowels /i/, /delta/, and /alpha/, respectively, were presented for identification. The results were compared with those of A. S. House and K. N. Stevens [J. Speech Hear. Disord. 21, 218-232 (1956)] and A. S. House [J. Speech Hear. Disord. 22, 190-204 (1957)] obtained with steady-state vowels and consonantal murmurs and with those of M. H. L. Hecker [J. Acoust. Soc. Am. 34, 179-188 (1962)]. Three conclusions emerged. First, the relationship between vowel height and the amount of velopharyngeal coupling needed for a nasal precept occurs in conditions where subjects are required to make linguistically relevant judgments. Second, the relationship can arise in conditions where vocalic coarticulation is present. Third, the relationship is not confined to vowels but can also be observed in the case of dynamically articulated consonants. One of the continua was also used for discrimination experiments, which yielded the classical pattern of high discriminability at the category boundary.